1. Field of the Invention:
This invention is directed to a new safety glass, intended particularly to be used as a windshield for motor vehicles.
The following description will deal with the case of windshields for motor vehicles, but it is understood that the invention can also relate to safety glasses intended to be mounted in any bay of a motor vehicle or building.
2. Description of the Prior Art:
Windshields now currently used are so-called "laminated" safety glasses, i.e., made up of two or more glass sheets glued by one or more plastic insert sheets, this insert generally being a polyvinyl butyral sheet.
For simplicity, the following description will refer to simple laminated glasses, i.e., glasses comprising two glass sheets glued by a plastic insert sheet, without, however, excluding from the scope of the invention other types of laminated glasses.
Like other plastics that can be used in this application, polyvinyl butyral is known for its sensitivity to moisture. When water vapor diffuses from the edge of the glass into the insert sheet, the plastic that it comprises absorbs the water. A reduction in the adherence of the insert to the glass occurs. Further, the phenomena of opacification of the glass appears on the periphery. This water absorption can occur both before mounting of the windshield in the body of the vehicle, for example, during shipment from the manufacturing plant to the mounting site and during storage. Diffusion of the water can also occur when the glass has already been mounted in the body, if care has not been taken to make sure that the fluid tightness at the frame is sufficient to prevent any penetration of moisture. In tropical countries, for example, laminated windshields are subjected to particularly harsh conditions. Consequently, in these hot countries with a high degree of humidity in the air, the phenomena of opacification and delamination are greatly increased.
The invention therefore has as its object to provide glasses, particularly laiminated windshields whose edges are made as fluid-tight as possible in regard to the moisture that might penetrate into the plastic insert, either before mounting of the windshield in the vehicle body of afterward. Simultaneously, the proposed fluid tightness means facilitate and simplify installation of the glass in the bay, particularly its mounting by gluing.